Analysis of Structural and Functional Differences of Glucans Produced by the Natively Released Dextransucrase ofLiquorilactobacillus hordeiTMW 1.1822

The properties of the glucopolymer dextran are versatile and linked to its molecular size, structure, branching, and secondary structure. However, suited strategies to control and exploit the variable structures of dextrans are scarce. The aim of this study was to delineate structural and functional differences of dextrans, which were produced in buffers at different conditions using the native dextransucrase released byLiquorilactobacillus(L.)hordeiTMW 1.1822. Rheological measurements revealed that dextran produced at pH 4.0 (M-W= 1.1 * 10(8)Da) exhibited the properties of a viscoelastic fluid up to concentrations of 10% (w/v). By contrast, dextran produced at pH 5.5 (M-W= 1.86 * 10(8)Da) was gel-forming already at 7.5% (w/v). As both dextrans exhibited comparable molecular structures, the molecular weight primarily influenced their rheological properties. The addition of maltose to the production assays caused the formation of the trisaccharide panose instead of dextran. Moreover, pre-cultures ofL. hordeiTMW 1.1822 grown without sucrose were substantial for recovery of higher dextran yields, since the cells stored the constitutively expressed dextransucrase intracellularly, until sucrose became available. These findings can be exploited for the controlled recovery of functionally diverse dextrans and oligosaccharides by the use of one dextransucrase type.

Automated summary

This study investigated the structural and functional differences of dextrans produced at different pH values and conditions using dextransucrase released by L. hordeiTMW 1.1822. It was found that pH and molecular weight significantly influenced the rheological properties of dextrans. Pre-culture conditions and the addition of maltose also played roles in affecting the production and types of dextrans.